I found a specific report by #NTSB in 1991 which is relevant, where the #FAA is named in the causal links of the accident.

NTSB admonishes the FAA:

…. The National Transportation Safety Board determines that the probable cause of this accident was the loss of control in flight as a result of a malfunction of the left engine propeller control unit which allowed the propeller blade angles to go below the flight idle position. Contributing to the accident was the deficient design of the propeller control unit by Hamilton Standard and the approval of the design by the Federal Aviation Administration.

The design did not correctly evaluate the failure mode that occurred during this flight, which resulted in an uncommanded and uncorrectable movement of the blades of the airplane’s left propeller below the flight idle position……